A genetic analysis of reovirus type 3 will be conducted. Three factor crosses will be continued to define reassortment. An analysis of selected mutant revertants, including backcrosses to wild type parent and peptide fingerprinting of the major capsid polypeptides will be initiated to determine the nature of the mutation (? frameshift) and if phenotypic suppression is occuring. A comparison of capsid proteins of different reovirus types will be performed to determine if selected regions of these proteins are more variable than others. These studies should allow an approach to understanding how reovirus evolves gene diversity.